Usually asphalt plants include some means of temporarily storing the mix produced by the plant. Typically large, upright storage "silos" are used for that purpose, each silo including a bin elevated so that trucks can drive beneath it for loading. When the plant is a portable, rather than a fixed one, the silo or silos must necessarily accompany it, and that in turn means the bins and the elevators or conveyors needed for filling them must be "knocked down", as it were, for travel and then resurrected at the new location.
There are many existing designs of portable silos for storage of asphalt and kindred products. Some erect the bin and conveyor bodily from a horizontal position in which they are transported, as in U.S. Pat. No. 4,337,014, for instance. Others elevate the bin relative to a bin support structure on a travel frame and then separately place the conveyor in position, as in U.S. Pat. Nos. 2,136,869; 2,207,303; 3,141,576; 3,142,390; 3,217,909; and 3,257,032, for example. Various "batcher" plants jointly elevate the conveyor and bin relative to the travel frame, such as in U.S. Pat. Nos. 2,310,592; 3,064,832; 3,251,484; and 3,406,839. But the bins in these cases are relatively small and are not really for storage in the sense here concerned.
More pertinent to the present invention are asphalt storage silos in which elevation of the bin also elevates the discharge end of the conveyor, the latter and the bin being carried together on a towed travel frame. An example of that approach is disclosed in U.S. Pat. No. 3,586,181. There the bin consists of two telescopic sections, the discharge end of the conveyor being attached to one of the sections. By a series of operations involving both raising and lowering the two bin sections relative to each other and their support structure and detaching and reattaching the discharge end of the conveyor to the bin sections as well as the support structure, the bin and conveyor are elevated to their working position. The disadvantages of this design are the multitude of steps required to elevate (and lower) the components, the need to detach and reattach the conveyor during both movements, and the very elongated travel frame needed to support the inlet end of the conveyor.
A modification of that design, marketed by CMI Corporation of Oklahoma City, Okla., pivots the conveyor intermediate its ends to the bin support structure and positions the conveyor when in its travel position so that it wholly overlies the bin, the latter being no longer of telescopic sections but of integral construction. In the travel position a pair of rear struts are pivotally attached between the inlet end of the conveyor and the rear of the travel frame, and a pair of telescopically adjustable forward struts are pivotally attached between the discharge end of the conveyor and the forward end of the travel frame. For erection the forward struts are first detached from the travel frame. A cable and winch system then tilts the conveyor about its pivot to an intermediate position in which its inlet end is on the ground. The conveyor is then detached from its pivot to the bin support structure and the forward pair of struts adjusted in length and attached to the upper front edge of the bin. A set of four winch and cable systems next elevates the bin and thus the discharge end of the conveyor to their final working position. The need for an elongated travel frame is thereby eliminated but detachment and reattachment of various components is still necessary when raising and lowering the conveyor and bin.
In another current portable asphalt storage silo, manufactured by Astec Industries, of Chattanooga, Tenn., and shown in U.S. Pat. No. 4,348,146, the bin is carried atop an articulated support structure pivoted to the travel frame so that it parallelogrammatically collapses onto the latter for transport. The conveyor is also attached adjacent its discharge end by an articulated linkage to the bin support structure and by a pivot adjacent its inlet end to the travel frame. Hence as the bin support structure is swung upright so is the conveyor. This approach avoids detachment and reattachment of components but requires an elaboration of heavy pivoted components as well as a somewhat elongated travel frame, both to support the inlet end of the conveyor and to accommodate the bin support structure when collapsed.
The chief object of the present invention is therefore to provide a portable asphalt storage silo in which the travel frame is relatively short and the bin and conveyor so interconnected to each other and the travel frame that both can be raised and lowered without the need to attach or detach any components in the process.